Air filtration media for air purification

ABSTRACT

An air filtration media for use with a heating ventilation and air condition (HVAC) system is provided. The filtration media comprises an air filter media layer having a first and second side, a PCO media layer having a first and second side, and a barrier layer positioned between the second side of the air filter media layer and the first side of the PCO media layer. The air filter media layer, barrier layer, and PCO layer are pleated together and enclosed within a frame for placement adjacent a light source within a plenum of the HVAC system.

CROSS-REFERENCED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/919,383 filed on Jun. 17, 2013. U.S. patent application Ser. No.13/919,383 is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure is directed, in general, to air filtration andpurification for heating ventilation and air conditioning (HVAC) systemsand, more particularly, to a photocatalytic oxidation (PCO) airfiltration media for air purification.

BACKGROUND

Indoor air can include trace amounts of contaminants: e.g., dust, smoke,carbon monoxide, as well as volatile organic compounds generated oroutgassed from the living space as a byproduct of our modern buildingmethods. As indoor air flows through the return ducts of a heating,ventilation and air conditioning (HVAC) system, the air first encountersa system air filter which blocks the passage of particulatecontaminants, and allows the return air to enter the portion of the HVACsystem where it is heated, cooled, humidified, or dehumidified.

While filters are essential in removing particulate contaminants fromthe air prior to conditioning, they only block the passage of someparticulate contaminants but do not destroy them. As a result, some airfiltration and purification systems utilize ultraviolet (UV) radiationin combination with air filters in HVAC systems to further kill airbornebacteria and viruses. Photocatalytic oxidation (PCO) air purificationsystems employ a photocatalytic coating, such as titanium dioxide, interalia, in combination with an activating photonic light source of aparticular wavelength to destroy indoor airborne contaminants includingvolatile organic compounds such as formaldehyde, toluene, propanol,butene, and acetaldehyde. The system arrangement commonly includes oneor more ultraviolet lamps, and a photocatalytic monolith, such as ahoneycomb, coated with the photocatalytic coating. Titanium dioxide,e.g., is well known as a photocatalyst in a fluid purifier to destroysuch contaminants.

SUMMARY

The present disclosure provides, in one aspect, an air filtration mediafor use with a heating ventilation and air condition (HVAC) system isdisclosed. The filtration media comprises an air filter media layerhaving a first and second side; and a PCO media layer having a first andsecond side. A barrier layer is positioned between the second side ofthe air filter media layer and the first side of the PCO media layer.The air filter media layer, barrier layer, and PCO layer may be pleatedtogether and enclosed within a frame for placement adjacent a lightsource within a plenum of the HVAC system. In some embodiments, thelight source may comprise an ultraviolet lamp and the PCO layer maycomprise either titanium dioxide or other photoreactive metalsemiconductor material.

In another aspect, a method of manufacturing an air purification systemfor use in plenum comprising a heating, ventilation and air condition(HVAC) system is provided. The method comprises providing an air filtermedia having a first side and a second side; and providing a PCO mediahaving a first side and a second side. The method further comprisespositioning a protective barrier between the second side of the airfilter media and the first side of the PCO media; and pleating the airfilter media, barrier, and PCO media into at least one pleating patternhaving multiple pleats and enclosing the at least one pleating patternwithin a frame. Next a light source is provided and positioned adjacentthe frame proximal to the second side of the PCO media, wherein theframe and light source are positionable within the plenum of the HVACsystem. In some embodiments, the barrier layer may be a laminate coatedonto the second side of the air filter media. In another embodiment, thebarrier layer may be a laminate coated onto the first side of the PCOmedia.

In yet another aspect a heating, ventilating and air conditioning (HVAC)air purification system, the air purification system comprising afiltration media, the filtration media enclosed within a frame. Thefiltration media comprises an air filter layer having a first and secondside; a photocatalytic oxidation (PCO) layer having a first and secondside; and a barrier layer between the second side of the air filterlayer and the first side of the PCO layer. An ultraviolet light sourceis adjacent to the filtration media proximal to the second side of thePCO layer, wherein the filtration media and light source are situatedwithin a plenum.

The foregoing has outlined features of the present disclosure so thatthose skilled in the pertinent art may better understand the detailed.Additional features of the disclosure will be described hereinafter thatform the subject of the claims. Those skilled in the pertinent artshould appreciate that they can readily use the disclosed conception andspecific embodiment as a basis for designing or modifying otherstructures for carrying out the same purposes of the present disclosure.Those skilled in the pertinent art should also realize that suchequivalent constructions do not depart from the spirit and scope of thepresent disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the disclosure, reference is nowmade to the following descriptions taken in conjunction with theaccompanying drawing, in which:

FIG. 1 is a schematic view of a conventional heating, ventilation andair conditioning (HVAC) system having a photocatalytic oxidation (PCO)subsystem and constructed according to the principles of the presentdisclosure;

FIG. 2 is a side view of one embodiment of a PCO subsystem according tothe present disclosure;

FIG. 3A illustrates one embodiment of an air filter/PCO media accordingto the present disclosure;

FIG. 3B illustrates another embodiment of an air filter/PCO mediaaccording to the present disclosure;

FIG. 3C illustrates yet another embodiment of an air filter/PCO mediaaccording to the present disclosure; and

FIG. 4 is a flow diagram of a method of manufacturing a PCO subsystemaccording to the present disclosure.

DETAILED DESCRIPTION

Ultraviolet (UV) lamps in PCO air purification applications generallyemit ultraviolet-wavelength photons within 360° around the longitudinalaxis of the lamps. While UV light is extremely useful in the airpurification and PCO applications, UV light is also harmful to certainmaterials commonly found in the HVAC system, such as the air filter.Exposure of UV radiation results in early degradation and decreasedsystem performance.

Traditional air filtration and purification systems require a certainamount of plenum and/or cabinet space to provide enough clearance withinthe cabinet for all of the components configured sequentially, thecomponents including an air filtration media, one or more protectivereflectors/light barriers, a light source, and a PCO media. These PCOsystems not only require an additional amount of clearance toaccommodate the spacing of the components but also can increaseinstallation and maintenance costs since each component may be installedand maintained separately. Certain UV bulbs are available whichincorporate the reflector/barrier and the light source as one component,which may simplify the maintenance and installation, but comprise ahigher component cost than traditional lamps without reflectors.

Accordingly, the present disclosure provides a heating, ventilation, andair conditioning (HVAC) air purification system that incorporates theair filtration media, protective barrier/reflector and PCO media into asingle, more compact filtration media that protects the air filter mediafrom UV light and photocatalytic oxidation, while not interfering in theair purification and PCO applications. An air purification systemutilizes the new air filtration media, the media enclosed in a frame andcomprising an air filter layer and a PCO layer positioned on opposingsides of a barrier layer. Air flow enters through the air filter layerand out from the PCO layer, wherein a light source, such as a UV lightsource, is positioned outside of the frame proximate to the PCO layer.The PCO layer and UV light source work together to destroy particulatecontaminates. The barrier layer protects the air filter layer fromdamage and destruction by the UV light source. Previous PCO purificationsystems have heretofore been unable to combine the separate filter mediawith the PCO media because of the damaging effects of UV light ontraditional filter media. Further, the combination of the two separatemedia would be counterintuitive because of various cost and physicallimitations in pleating PCO media, the lack of a protective barrier, andprevious design considerations utilizing the light source before the PCOmedia such that air flows through the UV light prior to encountering thePCO media.

Referring initially to FIG. 1, illustrated is a schematic view of aconventional heating, ventilation and air conditioning (HVAC) system 100having an air purification subsystem 102 and constructed according tothe principles of the present disclosure. The HVAC system 100 comprisesan outdoor portion 104, i.e., above line 108, and an indoor portion 106,i.e., below line 108. The outdoor portion 104 comprises a conventionalelectric motor-driven compressor 110 connected via a conduit 112 to aheat exchanger 114 disposed outdoors, typically, and comprising arefrigerant fluid primary condenser. In the embodiment illustrated inFIG. 1, heat exchange between refrigerant fluid flowing through thecondenser heat exchanger 114 and ambient air is controlled by a fan 118having plural fixed-pitch blades and which is driven by a variable speedelectric motor 120. The electric motor 120 may be anelectrically-commutated type operating on variable frequency and voltageAC electric power as supplied to the motor via a controller 122. Fan 118propels a heat exchange medium, such as ambient outdoor air 119, throughthe condenser heat exchanger 116. The condenser heat exchanger 116 mayalso operate with other forms of heat exchange media at controlled flowrates thereof. Control of heat exchange medium 119 flowing overcondenser heat exchanger 116 may take other forms such as a constantspeed variable pitch fan, air flow control louvers, or control of avariable flow of a liquid heat exchange medium. The condenser heatexchanger 116 is also operably connected to a conventional refrigerantfluid filter and dryer 124 disposed in a conduit 126 for conductingcondensed refrigerant fluid to a conventional refrigerant fluidexpansion device 140. A temperature sensor 134, disposed within aconditioned space 132 to be conditioned by the system 100, is alsooperably connected to the controller 122. Controlled/conditioned space132, as well as a return air path 155 from space 132, is representedschematically in the drawing figures.

The indoor portion 106 comprises the controller 122, a heat exchangerplenum 150, the air purification subsystem 102, a drive motor 152, amotor-driven blower 154, the refrigerant fluid expansion device 140, aheat exchanger 144, e.g. an evaporator, and the temperature sensor 134.Conduit 126 is operable to deliver refrigerant fluid to the conventionalrefrigerant fluid expansion device 140 and to the heat exchanger 144,respectively. The expansion device 140 includes a remote temperaturesensor 140 a which is adapted to sense the temperature of refrigerantfluid leaving the heat exchanger 144 by way of a conduit 146. Conduit146 is commonly known as the suction line leading to the compressor 110whereby refrigerant fluid in vapor form is compressed and recirculatedthrough the system 100 by way of condenser heat exchanger 116. Heatexchangers 116, 144 may be conventional multiple fin and tube typedevices, for example. One who is of skill in the art will understand thefunctioning of the HVAC heretofore described.

The air purification subsystem 102, within the heat exchanger plenum150, comprises a filtration media 160 enclosed within frame 162 andadjacent to a light source 164, which may comprise UV lamps or similarUV light sources known to those skilled in the art for use with PCOsystems. The filtration media 160 may comprise an air filter layer, aphotocatalytic oxidation (PCO) layer, and a barrier layer positionedbetween said filter layer and PCO layer pleated together. In oneembodiment, the PCO layer may comprise a metal media having aphotocatalyst coating. In another embodiment, the PCO layer may compriseany other photoreactive metal semiconductor material, including, but notlimited to, titanium dioxide (TiO₂), zinc oxide (ZO), tin dioxide(SnO₂), manganese trioxide (MnO₃), tungsten trioxide (WO₃), and dirontrioxide (Fe₂O₃), and various other photoreactive metal coatingmaterials. In some embodiments, the light source 164 may comprise a UVlamp. In a one embodiment, the light source 164 emits photons of aparticular wavelength to cause the photons to be absorbed by the PCOmedia, promoting an electron from the valence band to the conductionband, thus producing a hole in the valence band and adding an electronin the conduction band. The promoted electron reacts with oxygen, andthe hole remaining in the valence band reacts with water, formingreactive hydroxyl radicals. When a contaminant adsorbs onto thephotocatalyst, the hydroxyl radicals attack and oxidize the contaminantsto water, carbon dioxide, and other substances.

Referring now to FIG. 2, illustrated is shown one embodiment of an airpurification system 202 which may be used in the HVAC system 100 ofFIG. 1. The air purification system 202 comprises a frame 210 forenclosing filtration media 212. The filtration media 212 comprises anair filter layer 214 having a first and second side. A PCO media 216 ofthe filtration media 212 comprises a first and second side. A barrierlayer 218 may be positioned between the second side of the air filterlayer 214 and the first side of the PCO layer 216. Outside of the frame210, proximal to the second side of PCO layer 216 is a light source 220,which may comprise UV lamps and other similar UV light sources which maybe known in the art for use in conjunction with PCO media for removal ofair contaminants in an HVAC system. The purification system 202 may beenclosed within an enclosure 222 for placement within an HVAC system,the enclosure 222 comprising a plenum, cabinet, or other suitableenclosing structure for placement within an HVAC system.

The air filter layer 214 may comprise a fibrous membrane filter mediacomprising polypropelene, polyester, fiberglass, resins, or variousother fiber materials used in traditional air filter fabrication suchthat the filter media 214 may be folded into multiple pleats whileenabling uniform air flow through the air filter layer. In oneembodiment, the air filter layer 214 may comprise a high efficiencyparticulate air (HEPA) filter. The PCO layer 216 may comprise a metalmedia having a photocatalyst coating, including, but not limited totitanium dioxide and any other photo reactive metal semiconductormaterial for use in air purification systems.

The barrier layer 218 may comprise an independent layer between the airfilter layer 214 and PCO layer 216, but also be a laminate which isadhered onto either the second side of the air filter layer 214 or ontothe first side of the PCO layer 216 such that the barrier will be alight absorptive or reflective barrier for providing photo catalyticprotection for the air filter layer 214. Accordingly, the barrier layer218 may comprise coated or non-coated organic or inorganic materialssuch as polyester, glass, metal, or any non-photo-oxidizable, UVprotected and stabilized material which may be pleated and or adheredonto the air filter layer 214 or metal PCO layer 216, such that the airfilter layer 214 is protected from the UV or photocatalytic rays fromthe light source 220.

Referring now to FIG. 3A through 3C, there are shown three embodimentsof filtration media which may be utilized in the purification system 102according to the present disclosure. As shown in FIG. 3A, filtrationmedia 312 comprises an air filter layer 314, barrier layer 318, and PCOlayer 316 may be coupled altogether into a continuous sheet which ispleated into multiple uniform pleats. As shown in FIG. 3B, filtrationmedia 322 comprises air filter layer 324 and barrier layer 328 coupledtogether as one continuous sheet and pleated into multiple uniformpleats. PCO layer 326 is displaced adjacent the barrier layer 218, butpleated in a different pattern which is less dense in quantity of pleatsthan the number of air filter/barrier pleats, such that the PCO maystill react with an adjacent light source while enabling uniform airflowthrough filtration media 322. Referring now to FIG. 3C, there is shownanother embodiment of filtration media 332 comprising an air filterlayer 334 comprising a continuous sheet pleated into multiple uniformpleats. Adjacent the air filter layer 334 is barrier layer 338 and PCOlayer 336 pleated together in a different pleat pattern that is lessdense in pleats than the number of pleats of air filter layer 334, suchthat PCO layer 336 still reacts with an adjacent UV light source whilethe barrier layer 338 still protects the air filter layer 332.Accordingly, the air filter layer 332, barrier layer 338, and PCO layer336 may be pleated in various multiple pleating patterns, as long as auniform airflow is enabled through filtration media 332 in an HVACsystem and air filter layer 332 is protected from the adjacent lightsource.

Referring now to FIG. 4, there is shown a flow diagram of a method ofmanufacturing an air purification system according to the presentdisclosure. The method comprises, inter alia, providing an air filtermedia having a first side and a second side. A PCO media having a firstand second side is provided and a protective barrier is positionedbetween the second side of the air filter media and the first side ofthe PCO media. The air filter media, barrier, and PCO media may bepleated together, or in various combinations, into at least one pleatingpattern having multiple pleats and enclosing the at least one pleatingpattern within a frame. A light source, such as, e.g, a UV lamp, ispositioned adjacent the frame proximal to the second side of the PCOmedia; wherein the frame and light source are positionable within theplenum of a HVAC system. In some embodiments, the barrier layer may be alaminate coated onto the second side of the air filter media. In anotherembodiment, the barrier layer may be a laminate coated onto the firstside of the PCO media.

Although the present disclosure has been described in detail, thoseskilled in the pertinent art should understand that they can makevarious changes, substitutions and alterations herein without departingfrom the spirit and scope of the disclosure in its broadest form.

1. A method of manufacturing an air purification system for use in aplenum comprising a heating, ventilation and air condition (HVAC)system, the method comprising: providing an air filter media layercomprising a first side and a second side; providing a photocatalyticoxidation (PCO) media layer having a first side and a second side;positioning a barrier layer between the second side of the air filtermedia layer and the first side of the PCO media layer; pleating the airfilter media layer, the barrier layer, and the PCO media layer into atleast one pleating pattern; enclosing the at least one pleating patternwithin a frame; positioning the frame adjacent a light source thatproduces ultraviolet (UV) light; placing the frame and the light sourcewithin the plenum; and wherein the barrier layer comprises anindependent layer of coated glass that is configured to protect the airfilter media layer from the UV light produced by the light source. 2.The method according to claim 1, wherein the air filter media layer, thebarrier layer, and the PCO layer are folded together into a uniformmultiple pleat pattern.
 3. The method according to claim 1, wherein thePCO layer comprises a photo-reactive metal semiconductor material. 4.The method according to claim 1, wherein the air filter media layer is ahigh-efficiency particulate air (HEPA) filter.
 5. The method accordingto claim 1, wherein the PCO media layer comprises a photo-reactive metalsemiconductor material.
 6. The method according to claim 5, wherein thephoto-reactive metal semiconductor material comprises titanium dioxide.7. The method according to claim 1, wherein the barrier layer possesseslight-absorbing capabilities.
 8. The method according to claim 1,wherein the barrier layer possesses light-reflecting capabilities. 9.The method according to claim 1, wherein the air filter media layercomprises a fibrous membrane filter.
 10. A method for air purificationfor a heating, ventilation and air condition (HVAC) system, the methodcomprising: providing an air filter media layer and a photocatalyticoxidation (PCO) media layer within a frame; positioning a barrier layerbetween the air filter media layer and the PCO media layer; placing theframe comprising air filter media layer, the PCO media layer, and thebarrier layer adjacent a light source that produces ultraviolet (UV)light; wherein air flow enters through the air filter media layer andexits through the PCO media layer; wherein the PCO media layer and thelight source are configured to destroy air contaminates; and wherein thebarrier layer comprises an independent layer of coated glass that isconfigured to protect the air filter media layer from the UV lightproduced by the light source.
 11. The method according to claim 10further comprising pleating the air filter media layer, the barrierlayer, and the PCO media layer into at least one pleating pattern. 12.The method according to claim 10, wherein the PCO layer comprises aphoto-reactive metal semiconductor material.
 13. The method according toclaim 10, wherein the air filter media layer is a high-efficiencyparticulate air (HEPA) filter.
 14. The method according to claim 10,wherein the PCO media layer comprises a photo-reactive metalsemiconductor material.
 15. The method according to claim 14, whereinthe photo-reactive metal semiconductor material comprises titaniumdioxide.
 16. The method according to claim 10, wherein the barrier layerpossesses light-absorbing capabilities.
 17. The method according toclaim 10, wherein the barrier layer possesses light-reflectingcapabilities.
 18. The method according to claim 10, wherein the airfilter media layer comprises a fibrous membrane filter.